The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. These advances, however, have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed.
Various active and/or passive electronic components can be formed on a semiconductor IC. Capacitors are essential components for many ICs, such as sample-and-hold circuits, analog-to-digital (A/D) circuits, digital-to-analog (D/A) circuits and resonant circuits, switched-capacitor and continuous-time filters, as well as to many radio frequency (RF) applications. Capacitors are extensively used for many logic and other applications in the semiconductor manufacturing industry and are integrated into various types of semiconductor devices. Due to higher integration requirements to minimize costs associated with IC fabrication processes, the semiconductor manufacturing industry strives toward economization of each process step and minimization of chip size, while maximizing quality and functionality to the extent possible. Due to these trends of miniaturization or scaling of ICs to provide smaller ICs and improved performance, capacitor designs that consume low areas and possess high capacitance density are highly desirable.
Analog ICs generally employ various types of integrated capacitors utilizing metal-oxide-semiconductors (MOS) including p-n junction capacitors, metal-insulator-metal (MIM) capacitors, poly-to-poly capacitors, metal-oxide-metal (MOM) capacitors, and other structures. MOM capacitors, also known as vertical parallel plate (VPP) capacitors, can include natural vertical capacitors (NVCAPs), lateral flux capacitors, comb capacitors, interdigitated finger capacitors, etc. and are one of the most widely used MOS capacitors due to respective characteristics, e.g., high capacitance density, low parasitic capacitance, symmetric design, superior RF characteristics, good matching characteristics, and processing advantages.